How Would I Express This Equation Using the Distance Formula?

For each point, its distance from the fixed point (-3,0) is twice its distance from the fixed point (3,0).

My book gives me the simplified answer, but I can't figure out how to express it in the distance formula to show my work.

Also, if someone's kind enough, please express the following as well: "For each point, its distance from the fixed point (4,3) is 3 times its distance from the fixed point (-1,2)."

FYI, this isn't my homework. I just need to know how to do this for an upcoming test.

Oh, and an explanation of where to plug in numbers would be greatly appreciated.